JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tr>
        <td>1</td>
        <td>2</td>
        <td>3</td>
        <td>4</td>
        <td>5</td>
        <td>6</td>
        <td>7</td>
    </tr>
</table>

JavaScript

$('td').each(function(idx) {
    if (idx % 3) {
        return;
    } else {
        $(this).nextAll(':lt(2)').andSelf().wrapAll('<tr/>');
    }
}).parent().unwrap();